The Effects Of EPA And DHA On The Growth,Reproductive Performance And FAD, FAE MRNAs Expression In Rice Field Eel (Monopterus Albus)

In order to explore the requirement of ricefield eel(Monopterus albus, Zuiew) in EPA and DHA, and the mechanization of fatty acid metabolism. Four feeding experiments which the experimental diets contained different contents of EPA and DHA and different EPA/DHA ratios were conducted to investigate the influence of n-3LC-PUFA on growth and reproductive performance and fatty acid metabolism of rice field eel. In addition, the mRNA expression of desaturase (FAD)and elongase (FAE) genes in liver, muscle and gonad tissues,and some enzyme activities associated with fatty acid metabolism were also analysed. Fish were fed with diets containing different levels and ratios of n-3LC-PUFA respectively. The main results were shown as follows:1. The effects of different contents of EPA and DHA of dietary lipids on lipids metabolism, growth and reproductive performance of ricefield eelThree isonitrogenous and isolipidic experimental diets containing different levels of n-3LC-PUFA (0.00%,0.35%and0.70%, respectively) but the same DHA/DHA ratio (DHA:EPA=3:1) were fed to ricefield eel (average weight:21.71±0.54g)for60days. After taking samples, fifty female ricefield eels were picked up for reproductive experimenting. Results showed that EPA and DHA was able to promote lipids metabolism and improve the growth and reproductive performance of rice field eel, while in this test conditions, the better additive amount was0.70%.2. The effects of different EPA/DHA ratios of dietary lipids on lipids metabolism, growth and reproductive performance of ricefield eelThree isonitrogenous and isolipidic experimental diets containing similar content but different ratios of EPA/DHA ((EPA(0.36%):DHA(0.24%)=1.50,EPA(0.18%):DHA (0.52%)=0.35,EPA(0.00%):DHA(0.80%)=0.00), respectively) were fed to ricefield eel (average weight:21.73±0.15g) for60days. After taking samples, fifty female ricefield eels were picked up for reproductive experimenting. Results showed that an EPA/DHA ratio of0.35in the diet could promote lipid metabolism and improve the growth and reproductive performance of rice field eel.3. The effects of different levels of EPA and DHA of dietary lipids on tissues fatty acid composition and fatty acid desaturase (FAD) and elongase (FAE) mRNAs expression of rice field eel (Monopterus albus Zuiew)Three isonitrogenous and isolipidic experimental diets containing different levels of EPA and DHA (0.00%,0.33%and0.73%, respectively) were fed to ricefield eel (average weight:49.50±2.25g) for8weeks. Results showed that fatty acid profiles of liver, muscle and gonad reflected profiles of experimental diets;The liver was the main place for metabolizable of EPA and DHA; the short of DHA of dietary lipids could promote the convertion from EPA to DHA.4. The effects of the EPA/DHA ratio of dietary lipids on tissues fatty acid composition and fatty acid desaturase (FAD) and elongase (FAE) mRNAs expression of rice field eel (Monopterus albus Zuiew)Three isonitrogenous and isolipidic experimental diets containing similar content but different ratios of EPA/DHA (1.46,0.34and0.02, respectively) were fed to ricefield eel (average weight:50.05±3.06g) for8weeks. Results showed that ricefield eel have the ability of converting the EPA to DHA. Moreover high level of DHA could suppress the mRNAs expression of FAD.